The acquisition of MB Financial appears beneficial, Winter said in the upgrade note. (See the analyst's track record here.)

“MBFI is very [complementary] given very little commercial banking overlap and FITB has a stronger consumer bank; but MBFI has better branch locations,” the analyst said.

The deal increases Fifth Third's share in Chicago, its largest market, Winter said. As a merged entity, Fifth Third will rank No. 2 in retail deposits, No. 4 in total deposits and No. 2 in middle-market banking in the Chicago area, he said.

In order to reduce the risk of customer and employee attrition, Fifth Third will retain MB Financial’s senior management and bankers, the analyst said.

The Fifth Third-MB tie-up is expected to close in the first quarter of 2019 and generate $255 million in pretax savings, Winter said.

“Management identified $100 million in cost saves from legacy FITB with most of it being realized in 1Q19. Plus there is approximately 40 to 50 percent of earnings to be realized from its original $800 million target on [the bank's profit improvement program] Project NorthStar."

A run-off of commercial loans — $5 billion over two years — is in the rearview mirror, making Fifth Third's year-over-year comparisons easier and reducing its credit risk in the next downturn, according to Wedbush.

Price Action

Fifth Third shares were up 0.65 percent at $29.62 at the time of publication Tuesday, while MB Financial shares were 0.17 percent higher at $48.54.